I think the reason this isn't done more often is that most decisions making is political in nature. Explicitly stating downsides provides opponents of "the plan" a greater opportunity to continue arguing for their side in bad-faith.
Presenting only the upside gives enough context to helps the team execute the plan.
Another aspect is management trying to hide the distasteful aspects of decision making (e.g. choosing an "inferior" technology because it requires the company to invest more in training its staff)
I wish this wasn't the case and I dream of being part of an org where upsides/downsides are always explicitly stated but I am yet to find one (outside of very small teams within larger orgs) where complex politics doesn't have an oversized influence on decision making.
Presenting only the upside gives enough context to helps the team execute the plan.
Another aspect is management trying to hide the distasteful aspects of decision making (e.g. choosing an "inferior" technology because it requires the company to invest more in training its staff)
I wish this wasn't the case and I dream of being part of an org where upsides/downsides are always explicitly stated but I am yet to find one (outside of very small teams within larger orgs) where complex politics doesn't have an oversized influence on decision making.